I had a thought yesterday with big Bertha's sp defense power
Where on a 1-4 she ignores all but 1 damage and on a 5-6 she ignores everything.

What happens if you put life model decoy on her? It grants her toughness or reduces damage if not reduced by any other effect.

Big Bertha IGNORES not REDUCES. So would this make her nearly indestructible in golden age if say this feat was combined with fortitude?

On the surface that looks to be a legal combination of powers. If that was the case outside of incapacitate and Pulsewave she would be really hard to kill.

I know that you aren't supposed to be able to use two different damage reducing powers when dealing with damage dealt from the same attack or game effect. I don't know where in the rulebook or PG it says that so I can't quote it. That being said, even though Bertha's SP says it is ignoring the damage, I'd think you would still classify her defensive power as a damage reducer.

I had to look up LMD:
And the answer, straight from the 2013 Rulebook...

Specifically the rulebook says that if multiple effects would allow a character to reduce or ignore damage only one of them can apply.

Edit: Yeah, what Mike said.

Alright. On that wording through the rulebook.

How does the Hellfire club team base special attack power work? Where they reduce damage an additional 1? Doesn't that contradict this ruling since when they have that power they usually have impervious or invulnerable?

Maybe. It wouldn't be the first time, but what's the exact wording of the power in question? Without seeing that it's impossible to say.

That damage reducer is an exception to the rule because it specifically say that it works together with other damage reducers.

Special powers are allowed to "break" the rules. That's why they're special.